This invention relates generally to touch fasteners, and specifically to composite touch fasteners having both loops and loop-engageable fastener elements extending from one side of a common substrate, to their application in products such as closure strips for reclosable bags, and to methods and apparatus for their manufacture.
There has been much development over the last thirty years in the field of hook-and-loop fasteners. Early touch fastener products of this type consisted of two mating tapes, each being knit or woven. One tape would include loops of filament woven into a base, and the other would include filaments woven to form loops and then cut to form hooks. In some cases free ends of drawn plastic filaments on the male tape would be melted to form protruding heads. This shape of fastener element is sometimes called a xe2x80x9cmushroomxe2x80x9d, to distinguish it from xe2x80x9chookxe2x80x9d-shaped elements with re-entrant crooks.
More recently, continuous molding of fastener elements extending from a common sheet-form resin base has resulted in less expensive and thinner male tapes. Significant improvements in this area include the development of continuous fastener tape molding using fixed mold cavities (see Fischer, U.S. Pat. 4,794,028), and the ability to provide loops on the back side of the male fastener tape as the fastener tape substrate and elements are being formed (see Kennedy et al., U.S. Pat. 5,260,015), thus creating a composite fastener tape capable of fastening to itself. Further improvements have reduced the size of the fastener elements moldable by such techniques, to heights of 0.015 inch or less, which provide a very smooth touch when arranged in dense arrays.
As molded fastener tape has been improved to be more flexible and less expensive, it has found application in disposable garments, such as diapers. Further improvements are desirable to extend the applicability of molded touch fastener products to other uses.
One such use that is discussed in more detail below is as a closure for reclosable bags and other such packaging. Other types of repeated use closures for such bags include, for instance, the rib-and-groove type of closure such as is marketed under the name ZIPLOCK.
The invention features, in several of its aspects, a composite touch fastener product having both a band of loops and a band of hooks extending from a single face of a common, sheet-form substrate. Among other applications, this product can be included at the opening of a bag to function as a repeated use closure.
According to one aspect of the invention, an elongated closure strip includes a sheet-form resin substrate having a front face, a loop strip carried on the front face of the substrate, and an array of loop-engageable fastener elements integrally molded with resin of the front face of the substrate. The Loop strip comprises a non-woven web of fibers forming a discrete band of hook-engageable loops extending along the length of the closure strip, and the array of fastener elements forms a discrete band of fastener elements extending longitudinally along the length of the closure strip and spaced apart from the band of loops.
The closure strip is preferably constructed to be folded along a region between the bands of fastener elements and loops to place these bands in releasable engagement.
In some embodiments, the loop strip comprises a non-woven web of entangled fibers forming the loops and having a basis weight of less than about 4 ounces per square yard (preferably, less than about 2 ounces per square yard). In some cases, the non-woven web comprises a needled web in a stretched condition.
In some embodiments, fibers of the loop strip are affixed to the substrate across the width of the loop strip, such as by being encapsulated by resin of the substrate.
By xe2x80x9cwidthxe2x80x9d of the loop strip, we mean the entire transverse dimension of the preformed strip, as measured between the outermost edges of the preformed strip before it is attached to the substrate.
In many cases, the loop strip has a fiber density which is substantially constant across its width, yet the loop strip has discrete regions which are more encapsulated by resin than other regions of the loop strip. These discrete, more encapsulated regions may be spaced apart longitudinally along the loop strip, extend lengthwise along the loop strip and be spaced apart widthwise, or be arranged in a checkerboard pattern, for instance.
When we refer to regions of the loop strip as being more xe2x80x9cencapsulatedxe2x80x9d than other regions, we mean that the fibers of the more encapsulated regions are generally more thoroughly embedded in the resin of the substrate than the fibers of other regions. Generally, this will involve a deeper penetration of the substrate resin into the loop strip.
In some embodiments, longitudinal edge regions of the loop strip are affixed to the substrate, while a center region (between the edge regions) is substantially loose from the substrate. The center region of the loop strip may advantageously define a gentle arc extending away from the substrate in some of these embodiments.
In some configurations, a barrier layer (of a different material than the substrate) is included between the substrate and the loop strip. This barrier layer may be of paper or a polymer resin, for example.
In some cases the loop strip has at least one edge which is substantially loose from the substrate. This edge may be either an inner or outer edge in a finished bag, and can help to redirect peel separation forces to enhance the peel strength of the fastening.
In some closure strips, open-ended pockets are defined between an edge of the loop strip and the substrate. These pockets can also help to enhance peel strength in some cases.
In some embodiments, the edge regions of the loop strip have fibers directly encapsulated within resin of the substrate, while the closure strip also includes a binder (of a different material than the substrate) connecting fibers of the center region (between the edge regions) of the loop strip to resin of the substrate.
In some presently preferred embodiments, the substrate defines a pair of grooves extending longitudinally along the length of the closure strip between the band of loops and the band of fastener elements. These grooves are preferably lengthwise continuous and defined by molded surfaces in the front face of the substrate.
The closure strip also includes, in some cases, a longitudinal rib integrally molded with and extending from the front face of the substrate between the band of loops and the band of fastener elements. In some of these cases, the rib is disposed between the pair of grooves just described.
In some embodiments, the front face of the substrate has two longitudinal edge regions void of fastener elements and loops, for permanently adhering the substrate to the sides of a bag. These edge regions may be covered with a layer of adhesive for permanently attaching the closure strip to opposite sides of a bag, or comprise exposed resin of the substrate, for permanently welding the closure strip to opposite sides of a bag formed of a compatible material. These longitudinal edge regions may alternatively be disposed on the back face of the substrate.
The substrate of some embodiments of the closure strip is advantageously formed of polyethylene, such as for welding the substrate to polyethylene bag material.
Some embodiments of the closure strip also include an adhesive strip carried on the front face of the substrate between the band of fastener elements and the band of loops. The adhesive strip has an exposed surface arranged to contact the front face of the closure strip when the closure strip is folded to engage the loops with the fastener elements, to retain the closure strip in a folded state.
Alternatively, some embodiments have a first adhesive strip carried on the front face of the substrate between the band of fastener elements and the pair of grooves, and a second adhesive strip carried on the front face of the substrate between the band of loops and the pair of grooves. The first and second adhesive strips have exposed surfaces arranged to contact each other when the closure strip is folded to engage the loops with the fastener elements, to retain the closure strip in a folded state. In either case, these adhesive strips can advantageously provide an air-tight seal when the closure is closed.
In some embodiments, the closure strip includes a layer of paper permanently adhered to the substrate. In some cases, this layer of paper is carried on the front face of the substrate, in its longitudinal edge regions. In some cases, the paper is carried on the back face of the substrate. In some other cases, the layer of paper is disposed between a center region of the loop strip and the substrate.
According to a second aspect of the invention, an elongated closure strip includes a sheet-form resin substrate having rant and back faces, a loop strip carried on the front face of the substrate, and an array of loop-engageable fastener elements carried on the front face of the substrate. The loop strip forms a discrete band of hook-engageable, free-standing loops along the length of the closure strip, and the array of fastener elements forms a discrete band of fastener elements extending longitudinally along the length of the closure strip and spaced apart from the band of loops. The substrate defines a pair of grooves extending longitudinally along the length of the closure strip between the band of loops and the band of fastener elements, and a longitudinal rib integrally molded with and extending from the substrate between the pair of grooves.
In some embodiments, the loop strip comprises a non-woven web of entangled fibers forming the loops and having a basis weight of less than about 4 ounces per square yard (preferably, less than about 2 ounces per square yard).
In some cases, the grooves and rib are disposed on the front face of the substrate. In other cases, they are disposed on its back face.
Various embodiments of this aspect of the invention contain various features described above with respect to the first aspect of the invention.
According to a third aspect of the invention, an elongated closure scrip includes a sheet-form resin substrate having front and back faces, a loop strip carried on the front face of the substrate, and an array of loop-engageable fastener elements carried on the front face of the substrate. The loop strip forms a discrete band of hook-engageable, free-standing loops along the length of the closure strip, and the array of fastener elements forms a discrete band of fastener elements extending longitudinally along the length of the closure strip and spaced apart from the band of loops. The loop strip has width and a fiber density which is substantially constant across its width, and is at least partially encapsulated in resin of the substrate across its width, with the loop strip having discrete regions which are more encapsulated by resin than other regions of the loop strip.
Preferably, the fastener elements are integrally molded with resin of the substrate.
Various embodiments of this aspect of the invention contain various features described above with respect to the first aspect of the invention.
According to a fourth aspect of the invention, a reclosable bag includes a bag body and an elongated closure strip. The bag body has two opposing side walls joined along three edges to form therebetween a pouch having an open end. The closure strip is permanently affixed to the two side walls of the bag body along the open end, and includes a sheet-form resin substrate having a front face, a loop strip carried on the front face of the substrate, and an array of loop-engageable fastener elements integrally molded with resin of the front face of the substrate. The loop strip forms a discrete band of hook-engageable, free-standing loops along the length of the closure strip, and the array of fastener elements forms a discrete band of fastener elements extending longitudinally along the length of the closure strip and arranged to engage the band of loops to releasably retain the bag in a closed condition when the opposing sides of the bag body are pressed together at the open end.
Preferably, the loop strip of the closure strip comprises a non-woven web of entangled fibers forming the loops and having a basis weight of less than about 4 ounces per square yard (more preferably, less than about 2 ounces per square yard).
In some embodiments, the substrate of the closure strip defines a pair of grooves extending longitudinally along the length of the closure strip between the band of loops and the band of fastener elements, the pair of grooves spaced apart to define between them a band of substrate resin for retaining the bag in a closed condition until the closure scrip is torn along the pair of grooves.
For some applications, the substrate is continuous and solid between the band of loops and the band of hooks and forms a seal to retain the bag in a sealed condition until the closure strip is torn along the pair of grooves.
In some embodiments, the substrate of the closure strip is permanently affixed to the side walls of the bag body with adhesive. In some other embodiments, the substrate of the closure strip is welded to the side walls of the bag body. The substrate of the closure strip and the side walls of the bag body may both be formed of polyethylene, for Instance.
The closure strips of various embodiments of this aspect of the invention contain various features described above with respect to the first aspect of the invention.
According to a fifth aspect of the invention, a reclosable bag includes a bag body having two opposing side walls joined along three edges to form a pouch having an open end, and a closure strip permanently affixed to the two side walls of the bag body along the open end. The closure strip includes a sheet-form resin substrate having a front face, a loop strip carried on the front face of the substrate, and an array of loop-engageable fastener elements carried on the front face of the substrate. The loop strip forms a discrete band of hook-engageable, free-standing loops along the length of the closure strip, and the array of loop-engageable fastener elements forms a discrete band of fastener elements extending longitudinally along the length of the closure strip and arranged to engage the band of loops to releasably retain the bag in a closed condition when the opposing sides of the bag body are pressed together at the open end. The substrate defines a pair of grooves extending longitudinally along the length of the closure strip between the band of loops and the band of fastener elements, the pair of grooves spaced apart to define between them a band of substrate resin for retaining the bag in a closed condition until the closure strip is torn along the pair of grooves. The substrate also defines a longitudinal rib integrally molded with and extending from the substrate between the pair of grooves, the rib having thickness and arranged to be grasped between adjacent regions of the substrate and pulled to tear the closure strip along the pair of grooves.
In some embodiments, the substrate is continuous and solid between the band of loops and the band of hooks and forms a seal to retain the bag in a sealed condition until the closure strip is torn along the pair of grooves.
Preferably, the fastener elements are integrally molded with resin of the substrate.
According to a sixth aspect of the invention, a method of fabricating a closure strip is provided. The closure strip is in the form of a sheet-form resin substrate having a front face, with both a loop strip and an array of loop-engageable fastener elements carried on the front face of the substrate. The loop strip has width and forms a discrete band of hook-engageable, extended loops along the length of the closure strip. The array of loop-engageable fastener elements forms a discrete band of fastener elements extending longitudinally along the length of the closure strip and spaced apart from the band of loops, the substrate having a frangible section between the band of loops and the band of fastener elements. The method includes the steps of molding a continuous, sheet-form substrate having both a band of fastener elements integrally molded with and extending from its front face, and a frangible section, and attaching a continuous strip of loop material to resin forming the front face of the substrate to form a band of loops, with the frangible section of the substrate disposed between the band of loops and the band of fastener elements.
In some embodiments, the frangible section defines a pair of longitudinally extending grooves in the substrate, and the step of molding includes forming the grooves in the substrate as the substrate is formed. The step of molding also includes, in some instances, simultaneously forming a longitudinal rib extending from the substrate between the pair of grooves. In some cases, the rib and grooves are molded on the front face of the substrate.
In some embodiments, the step of attaching encapsulates fibers of the strip of loop material in resin of the substrate across the width of the strip of loop material.
In some embodiments where the strip of loop material has a fiber density which is substantially constant across its width, the step of attaching includes permanently bonding discrete regions of the strip of loop material to the substrate while leaving other regions of the strip of loop material in a less bonded condition.
In some embodiments of the method, the strip of loop material is permanently attached to the substrate after the substrate is molded. For instance, the strip of loop material may be attached to the substrate by heating the front face of the substrate and then pressing the loop material against the front face of the substrate with the front face of the substrate at an elevated temperature.
In some other embodiments, the strip of loop material is permanently attached to the substrate as the substrate is molded. For instance, in one preferred method the steps of molding and attaching include continuously feeding the strip of loop material through a nip defined between a rotating mold roll and a pressure roll (the rotating mold roll defining a multiplicity of cavities about its periphery for molding the fastener elements) while continuously introducing molten resin to the mold roll under conditions which cause the resin to fill the cavities and form the substrate, such that pressure in the nip bonds the strip of loop material to resin of the substrate.
In some cases, the mold roll has two extending ridges that form a pair of grooves in the substrate.
The step of molding, in some embodiments, includes simultaneously forming a longitudinal rib extending from the substrate between the pair of grooves (the mold roll defining, between is two ridges, a channel for forming the longitudinal rib).
In some other embodiments in which the strip of loop material is permanently attached to the substrate as the substrate is molded, the steps of molding and attaching include continuously feeding the strip of loop material through a gap defined between a rotating mold roll and a stationary extrusion head (the rotating mold roll defining a multiplicity of cavities about its periphery for molding the fastener elements), while continuously introducing molten resin to the gap under conditions which cause the resin to fill the cavities and form the substrate and to permanently adhere to the strip of loop material.
For some applications the method also includes, while continuously feeding the strip of loop material through the gap, continuously feeding a strip of preformed material through the gap between the strip of loop material and the extrusion head, such that the preformed material inhibits the encapsulation of fibers of the strip of loop material in predetermined regions and the preformed material is incorporated into the closure strip.
This preformed material is preferably selected from the group consisting of paper, fabric and plastic film, and may have perforations through it for allowing heavier penetration of substrate resin in some predetermined areas.
The closure strips employed in various embodiments of this aspect of the invention contain various features described above with respect to the first aspect of the invention.
According to a seventh aspect of the invention, a method of fabricating reclosable bags is provided. The method includes the steps of:
(a) providing a continuous length of sheet-form plastic, folded along its length and having two exposed longitudinal edges;
(b) providing a continuous closure strip folded along its length and having two exposed longitudinal edges (the closure strip having a sheet-form resin substrate with a front face, a loop strip carried on the front face of the substrate and forming a discrete band of hook-engageable, free-standing loops along the length of the closure strip, and an array of loop-engageable fastener elements integrally molded with the front face of the substrate and forming a discrete band of fastener elements extending longitudinally along the length of the closure strip and spaced apart from the band of loops, as described above);
(c) permanently attaching the longitudinal edges of the sheet-form plastic to the longitudinal edges of the closure strip to form a continuous preform tube; and
(d) forming sealed individual bags from the preform tube.
In some embodiments, the step of forming sealed individual bags includes cutting the continuous preform tube to predetermined lengths (each cut length comprising a section of closure strip and a section of sheet-form plastic), sealing a first open end of each cut length of preform tube, and sealing a second open end of each cut length of preform tube to form a sealed bag. In many cases, between the steps of sealing the first and second open ends, each cut length of preform tube is filled with material to be stored in the sealed bag.
In some embodiments, the step of forming sealed individual bags includes:
(d1) sealing the tube at a sealing point spaced from one end of the tube to form an end pouch with a single opening;
(d2) filling the end pouch with material;
(d3) sealing the single opening of the end pouch to form a sealed bag containing the material;
(d4) separating the sealed bag from the tube by severing the tube below the sealing point;
(d5) advancing the tube; and
(d6) repeating steps (d1) through (d5).
In some embodiments, the substrate of the closure strip defines a pair of grooves extending longitudinally along the length of the closure strip between the band of loops and the band of fastener elements, with the pair of grooves spaced apart to define between them a band of substrate resin for retaining the bag in a closed condition until the closure strip is torn along the pair of grooves.
The closure strips employed in various embodiments of this aspect of the invention contain various other features described above with respect to the first aspect of the invention.
According to an eighth aspect of the invention, a composite touch fastener has an elongated, sheet-form resin substrate with a front face, a fibrous loop strip partially encapsulated in resin of the front face of the substrate, and an array of loop-engageable fastener elements integrally molded with resin of the front face of the substrate. The loop strip forms a discrete band of hook-engageable, free-standing loops along the length of the substrate, the loop strip having a substantially constant fiber density across its width between its two longitudinal edges. The array of loop-engageable fastener elements forms a discrete band of fastener elements extending longitudinally along the substrate.
In some embodiments, the loop strip comprises a non-woven web of entangled fibers forming the loops. Preferably, the web has a basis weight of less than about 4 ounces per square yard (more preferably, less than about 2 ounces per square yard). The non-woven web may be in the form of a needled web in a stretched condition, for instance.
Various composite touch fasteners of this aspect of the invention contain features described above with respect to the first aspect of the invention.
According to a ninth aspect of the invention, a composite touch fastener includes an elongated, sheet-form resin substrate, a fibrous loop strip partially encapsulated in resin of the substrate, with the loop strip having discrete regions which are substantially more encapsulated by resin than other regions thereof, and an array of loop-engageable fastener elements integrally molded with resin of the substrate.
In some embodiments, the loop strip has a substantially constant fiber density across its width.
In some cases, the strip of loop material has regions of substantially higher loft than regions corresponding to the discrete regions which are substantially more encapsulated by resin.
By xe2x80x9cloftxe2x80x9d, we mean the distance the exposed loops of the loop material extend from the front face of the substrate, as presented for engagement by fastener elements.
In some embodiments, the strip of loop material comprises a non-woven web of entangled fibers forming the loops and having a basis weight of less than about 4 ounces per square yard.
Various composite touch fasteners of this aspect of the invention contain features described above with respect to the first aspect of the invention.
According to a tenth aspect of the invention, a method of fabricating a composite touch fastener is provided. The composite touch fastener is in the form of an elongated, sheet-form resin substrate having a front face, with both a loop strip and an array of loop-engageable fastener elements carried on the front face of the substrate. The loop strip has width and forms a discrete band of hook-engageable, exposed loops extending longitudinally along the substrate. The array of loop-engageable fastener elements forms a discrete band of fastener elements extending longitudinally along the length of the substrate. The method includes the steps of molding a continuous, sheet-form substrate having a band of fastener elements integrally molded with and extending from its front face, and attaching a continuous strip of loop material to resin forming the front face of the substrate to form a band of loops.
Preferably, the strip of loop material comprises a non-woven web of entangled fibers forming the loops and having a basis weight of less than about 4 ounces per square yard (more preferably, less than about 2 ounces per square yard)
In some embodiments, the strip of loop material has a fiber density which is substantially constant across its width, yet the step of attaching permanently bonds discrete regions of the strip of loop material to the substrate while leaving other regions of the strip of loop material in a less bonded condition.
In some cases, the strip of loop material is permanently attached to the substrate as the substrate is molded. For instance, in some preferred methods, the steps of molding and attaching include continuously feeding the strip of loop material through a gap defined adjacent a rotating mold roll (defining a multiplicity of cavities about its periphery for molding the fastener elements), while continuously introducing molten resin to the mold roll under conditions which cause the resin to fill the cavities and form the substrate, such that pressure in the gap bonds the strip of loop material to resin of the substrate.
In some cases, the gap is a nip defined between the mold roll and a pressure roll.
In some other cases, the gap is defined between the mold roll and a fixed extrusion head.
In some embodiments, the mold roll contains at least one staking ring having a contoured outer edge, the staking ring arranged to hold a predetermined region of the strip of loop material against the resin under pressure in the gap.
In one presently preferred configuration, the outer edge of the staking ring has protrusions spaced about its periphery, the protrusions corresponding to discrete regions of relatively greater encapsulation of the strip of loop material.
In some cases, the mold roll has multiple staking rings arranged to produce a predetermined bonding pattern across the strip of loop material.
According to a eleventh aspect of the invention, a method of fabricating a composite touch fastener is provided. The touch fastener is in the form of an elongated sheet-form resin substrate carrying both a preformed material and an array of loop-engageable fastener elements integrally molded with the substrate. The method includes molding a continuous, sheet-form substrate having a band of fastener elements integrally molded with and extending from the substrate, by continuously introducing molten resin to a gap defined adjacent a rotating mold roll defining a multiplicity of cavities about its periphery for molding the fastener elements, under conditions which cause the resin to fill the cavities and form the substrate, while permanently attaching a continuous strip of preformed material to resin of the substrate in a nip defined between the mold roll and a pressure roll, by causing pressure variations within the nip. The pressure variations result in regions of relatively high penetration of substrate resin into the preformed material and regions of relatively low penetration of substrate resin into the preformed material.
In some preferred embodiments, the mold roll has protrusions extending radially into the nip, for causing local increases in nip pressure chat correspond to the regions of relatively high penetration of substrate resin.
In some embodiments, the pressure roll has protrusions extending radially into the nip, the protrusions causing local increases in nip pressure that correspond to the regions of relatively high penetration of substrate resin.
In some cases, the cap and the nip are coextensive. In some other cases, the gap is defined between the mold roll and a fixed extrusion head.
In some embodiments, the regions of relatively high penetration of substrate resin into the preformed material are arranged in a checkerboard pattern along the strip of preformed material.
In some configurations, the array of fastener elements is disposed on a front face of the substrate and the strip of preformed material is attached to a back face of the substrate. The preformed material is, in some embodiments, coextensive with the back face of the substrate.
In some other configurations, the strip of preformed material and the array of fastener elements are both disposed on a common side of the substrate.
In some embodiments, the strip of preformed material comprises a strip of loop material having exposed loops arranged for releasable engagement by the fastener elements.
According to a twelfth aspect of the invention, an apparatus for fabricating a composite touch fastener is provided. The composite touch fastener, as described above, is in the form of an elongated sheet-form resin substrate having a front race, a loop strip carried on the front face of the substrate (the loop strip having width and forming a discrete band of hook-engageable, extended loops along the length of the touch fastener), and an array of loop-engageable fastener elements carried on the front face of the substrate and forming a discrete band of fastener elements extending longitudinally along the substrate. The apparatus includes a rotating mold roll defining a multiplicity of fixed cavities about its periphery for molding the fastener elements, means of supplying molten resin to the mold roll under conditions which cause the resin to fill the cavities and form the substrate, means of supplying a continuous strip of loop material between the molten resin and the mold roll under conditions which cause the strip of loop material to permanently bond to the front face of the substrate, and means of stripping the fastener elements from the cavities. The xe2x80x9cmeansxe2x80x9d elements of the apparatus will be understood to be those discussed or represented schematically herein or in the disclosures incorporated by reference, and their equivalents.
As a repeated use closure, the product of the invention provides a ventilated, easily alignable seal. As the bands of loops and fastener elements are relatively wide, there is no need for accurate alignment to form a reliable closure. The closure is able to accommodate a fair amount of dirt or debris without losing its function as a closure, making it particularly applicable as a closure for bags containing granular or powder substances. In addition, the natural porosity of the closure can provide some degree of filtering of airborne dust. Such a ventilated closure can be particularly desirable in cargo containers of airplanes in order to accommodate pressure changes, and, by its venting action, may help to avoid moisture buildup to keep produce and other such items fresh. The groove and rib tear strip molded into the center of the closure strip in some cases advantageously maintains an air-tight seal until the bag is initially opened. The continuous closure strip provided by the invention is readily adaptable to standard bag-making equipment and, in many instances, is directly weldable to compatible bag materials. These advantages accrue to bags produced according to the invention and having such a repeated use closure.
If made of an appropriate width, the closure strip of the invention can be folded and sealed to itself to form an enclosed bag.
By employing a very light, non-woven loop material and integrally molded fastener elements in several instances, the resulting product is relatively inexpensive and flexible.
The product of the invention is also useful in other applications, either as a packaging closure or as a general purpose fastener. Encapsulating fibers of the loop material in a predetermined pattern of alternating regions of light and heavy encapsulation can produce regions of particularly high loft in which hook-engageable fibers are particularly well-presented for engagement.
As a method of producing fastener products, the invention also provides a reliable method of securing very lightweight loop materials to the front face of a resin substrate having fastener elements, in many cases without adhesives and while the substrate and fastener elements are themselves being formed, eliminating a post-forming attachment step. The method does not require the loop material to have a variable fiber density to provide for variable resin penetration, and can therefore accommodate and locally bond loop materials having a homogeneous fiber density. As fibers of the loop material are, in many instances, directly encapsulated within resin of the substrate, undesirable delamination of loop material from the substrate is avoided during high peel loads. And, as the fastener elements are, in many cases, integrally molded with the substrate, delamination between the fastener elements and the substrate is also avoided. The fastener elements and resin substrate (including any tear strip features such as ribs and grooves appropriate for closure strips) can be molded in a single continuous process from the same flow of resin, with the loop material fed right through the substrate-forming gap or nip on the side of the resin adjacent the fastener element-forming mold roll.
By appropriately controlling the forming speed and resin temperature and pressure (the optimal values of which are interdependent and will depend on the type of resin employed and the geometry of the product, as will be understood by those of normal skill in the art), the resulting penetration of substrate resin into the loop material may be controlled so as to not completely flood the exposed surface of loops with resin. In many applications, the use of appropriately contoured staking rings in the region of the mold roll adjacent the loop material can help to form a pattern of lofted regions of loop material which are less penetrated by resin than other areas. Such lofted regions can extend loops for ready engagement by fastener elements.
The apparatus of the invention can provide an efficient means of carrying out the steps of the inventive method described above, to produce a continuous strip of fastener product.
Other features and advantages of the invention will be apparent from the following description of embodiments, and from the claims.